The Mediating Role of Normal Triglyceride Levels on Lymphocyte Populations in Abdominal Obesity: A Cross‐Sectional Study

Background and Aims: Abdominal obesity is linked to an increased risk of non-communicable diseases (NCD) and may affect immune function, particularly lymphocyte subpopulations. Waist circumference (WC) is a common indicator of abdominal obesity, but its relationship with lymphocyte subsets is unclear. The role of triglycerides (TG) in this context remains uncertain. This study aims to investigate the relationship between WC and lymphocyte subpopulations, while also evaluating TG's potential mediating effect. Methods: A retrospective analysis was conducted on physical examination records from March 2021 to September 2023, excluding incomplete data or extreme values. A total of 1836 records with normal TG was analyzed using t-tests, linear regression, and mediation analysis via SPSS 29.0 software. Results: After adjusting for confounders, WC was significantly positively correlated with CD3+ T cell count, CD4+ T cell count, and overall lymphocyte count, with TG demonstrating a full mediating effect (Beta [95% CI]: 2.11 [1.39-2.91], 1.39 [0.93-1.89], and 2.83 [1.86-3.87], respectively). WC were also correlated with B cell count, with TG showing a partial mediating effect (Beta [95% CI]: 0.65 [0.44-0.87], with a mediation effect ratio of 30.37%, and 0.02 [0.01-0.02], with a mediation effect ratio of 33.33%). Conclusion: In health checkups, individuals with normal TG levels, TG plays a significant mediating role in the changes of lymphocyte subpopulations related to abdominal obesity, particularly exerting a positive influence on CD4+ T cells and B cells, with no significant effect on NK cell numbers. These findings provide new insights into the relationship between abdominal obesity and immune dysregulation.